Physics 223 - Fall 2008 - Quiz #6
Name:
**Circle the correct answer from the choices provided with each question. In addition, you must justify your selection
of an answer. You may show your mathematical work, provide a clear definition, or eliminate the incorrect answers.
Only partial credit will be given if a clear justification is not provided.
1) A solid disk and a steel hoop are set side by side, released from rest at the same moment, and roll down
and the hoop has a radius Rhoop.The disk
an inclined plane towards its bottom. The disk has a radius hiSk
has a mass Mdiskand the hoop has a mass Mhoop.Choose the most definitive statement.
The ring is always slower than the disk ...
1. if Rhoop= %isk
2. if Mhoop= Mdisk
3. if Rhoop= Rdiskand Mhoop= Mdisk
4. regardless of the values of mass and radius.
2) A box, with its center-of-mass off-center (as indicated by the dot), is placed on an inclined plane. In
which of the four orientations shown, if any, does the box tip over?
5. None of the orientations will cause the box to top over.
3) A 1kg rock is suspended by a mass less string from one end of a l m measuring stick. What is the weight
of the measuring stick if it is balanced by a support force at the 0.25m mark?
1. 0.25kg
2. 0.5kg
3. lkg
4.2kg
5.4kg
6. impossible to determine
4) Two spheres look identical and have the same mass. One is hollow and the other is solid. Which method
would determine which is which?
1. Roll them down an incline.
2. Drop them from the same height.
3. Weigh them on a scale.
4. None of these
5 ) Two objects, of masses 6 and 8 kilograms, are hung from the ends of a stick that is 70 centimeters long
and has marks every 10 centimeters, as shown. If the mass of the stick is negligible, at which of the points
indicated should a cord be attached if the stick is to remain horizontal when suspended from the cord?
BONUS: Refer to the two pictures illustrated below to answer the problem. Rank each based on how
difficult it would be for the student to keep the meter stick from rotating. Explain your answer. If they are
both the same degree of difficulty, then also explain why.